Human Basal and Suprabasal Keratinocytes Are Both Able to Generate and Maintain Dermo-Epidermal Skin Substitutes in Long-Term In Vivo Experiments

Human Dermal Microvascular Arterial and Venous Blood Endothelial Cells and Their Use in Bioengineered Dermo-Epidermal Skin Substitutes

The bioengineering of vascular networks is pivotal to create complex tissues and organs for regenerative medicine applications. However, bioengineered tissues comprising an arterial and venous plexus alongside a lymphatic capillary network have not been explored yet. Here, scRNA-seq is first employed to investigate the arterio-venous endothelial cell marker patterning in human fetal and juvenile skin. Transcriptomic analysis reveals that arterial and venous endothelial cell markers NRP1 (neuropilin 1) and NR2F2 (nuclear receptor subfamily 2 group F member 2) are broadly expressed in fetal and juvenile skin. In contrast, expression of NRP1 and NR2F2 on the protein level is cell-type specific and is retained in 2D (2-dimensional) cultures in vitro. Finally, distinct arterial and venous capillaries are bioengineered in 3D (3-dimensional) hydrogels and rapid anastomosis is demonstrated with the host vasculature in vivo. In summary, the bioengineering of human arterial, venous, and lymphatic capillaries is established, hence paving the way for these cells to be used in regenerative medicine and future clinical applications.

Characterization of Human Skin Derived Cells by Raman Micro-Spectroscopy

Studying human skin biology can aid in understanding the pathophysiology of skin diseases and developing novel therapies, including tissue engineering approaches. Among various optical and spectroscopic techniques, Raman micro-spectroscopy stands out. This non-invasive method requires minimal sample preparation and provides molecular-level information on healthy and diseased cell types. The following chapter aims to provide a comprehensive guide to the basic methods of Raman micro-spectroscopy analysis of human epidermal samples from the perspective of their biochemical-molecular relationship, without the need for a deep and specialized knowledge in the field of spectroscopy. We do this based on two distinct examples: (1) Unstained cell subpopulations identified by hierarchical cluster analysis are compared with antibody treated sorted cell populations, and (2) skin cell type-specific molecular features are determined, and the composition of unknown cellular mixtures is revealed.

AQP1 differentially orchestrates endothelial cell senescence

Accumulation of senescent endothelial cells (ECs) with age is a pivotal driver of cardiovascular diseases in aging. However, little is known about the mechanisms and signaling pathways that regulate EC senescence. In this report, we delineate a previously unrecognized role of aquaporin 1 (AQP1) in orchestrating extracellular hydrogen peroxide (H2O2)-induced cellular senescence in aortic ECs. Our findings underscore AQP1's differential impact on senescence hallmarks, including cell-cycle arrest, senescence-associated secretory phenotype (SASP), and DNA damage responses, intricately regulating angiogenesis. In proliferating ECs, AQP1 is crucial for maintaining angiogenic capacity, whereas disruption of AQP1 induces morphological and mitochondrial alterations, culminating in senescence and impaired angiogenesis. Conversely, Aqp1 knockdown or selective blockade of AQP1 in senescent ECs rescues the excess H2O2-induced cellular senescence phenotype and metabolic dysfunction, thereby ameliorating intrinsic angiogenic incompetence. Mechanistically, AQP1 facilitates H2O2 transmembrane transport, exacerbating oxidant-sensitive kinases CaMKII-AMPK. This process suppresses HDAC4 translocation, consequently de-repressing Mef2A-eNOS signaling in proliferating ECs. However, in senescent ECs, AQP1 overexpression is linked to preserved HDAC4-Mef2A complex and downregulation of eNOS signaling. Together, our studies identify AQP1 as a novel epigenetic regulator of HDAC4-Mef2A-dependent EC senescence and angiogenic potential, highlighting its potential as a therapeutic target for antagonizing age-related cardiovascular diseases.

Glycan Modifications as Regulators of Stem Cell Fate

Glycosylation is a process where proteins or lipids are modified with glycans. The presence of glycans determines the structure, stability, and localization of glycoproteins, thereby impacting various biological processes, including embryogenesis, intercellular communication, and disease progression. Glycans can influence stem cell behavior by modulating signaling molecules that govern the critical aspects of self-renewal and differentiation. Furthermore, being located at the cell surface, glycans are utilized as markers for stem cell pluripotency and differentiation state determination. This review aims to provide a comprehensive overview of the current literature, focusing on the effect of glycans on stem cells with a reflection on the application of synthetic glycans in directing stem cell differentiation. Additionally, this review will serve as a primer for researchers seeking a deeper understanding of how synthetic glycans can be used to control stem cell differentiation, which may help establish new approaches to guide stem cell differentiation into specific lineages. Ultimately, this knowledge can facilitate the identification of efficient strategies for advancing stem cell-based therapeutic interventions.

Isolation, Characterization, and Utilization of Human Skin Basal and Suprabasal Epidermal Stem Cells

Studying human skin biology can aid in comprehending the pathophysiology of skin diseases and developing novel cell-based therapies, including tissue engineering approaches. This chapter provides a comprehensive guide of methods to determine human skin samples from the perspective of their cellular compositions. We describe as useful technique the histological analysis of tissue sections. We further illustrate the biological characterization of isolated and cultured basal and suprabasal interfollicular keratinocytes by cell sorting, cytospin immunostaining, colony forming efficiency, and long-term dermo-epidermal organotypic cultures.

Effects of an Adipose Mesenchymal Stem Cell-Derived Conditioned medium and TGF-β1 on Human Keratinocytes In Vitro

Human keratinocytes play a crucial role during skin wound healing and in skin replacement therapies. The secretome of adipose-derived stem cells (ASCs) has been shown to secrete pro-healing factors, among which include TGF-β1, which is essential for keratinocyte migration and the re-epithelialization of cutaneous wounds during skin wound healing. The benefits of an ASC conditioned medium (ASC-CM) are primarily orchestrated by trophic factors that mediate autocrine and paracrine effects in keratinocytes. Here, we evaluated the composition and the innate characteristics of the ASC secretome and its biological effects on keratinocyte maturation and wound healing in vitro. In particular, we detected high levels of different growth factors, such as HGF, FGFb, and VEGF, and other factors, such as TIMP1 and 4, IL8, PAI-1, uPA, and IGFBP-3, in the ASC-CM. Further, we investigated, using immunofluorescence and flow cytometry, the distinct effects of a human ASC-CM and/or synthetic TGF-β1 on human keratinocyte proliferation, migration, and cell apoptosis suppression. We demonstrated that the ASC-CM increased keratinocyte proliferation as compared to TGF-β1 treatment. Further, we found that the ASC-CM exerted cell cycle progression in keratinocytes via regulating the phases G1, S, and G2/M. In particular, cells subjected to the ASC-CM demonstrated increased DNA synthesis (S phase) compared to the TGF-β1-treated KCs, which showed a pronounced G0/G1 phase. Furthermore, both the ASC-CM and TGF-β1 conditions resulted in a decreased expression of the late differentiation marker CK10 in human keratinocytes in vitro, whereas both treatments enhanced transglutaminase 3 and loricrin expression. Interestingly, the ASC-CM promoted significantly increased numbers of keratinocytes expressing epidermal basal keratinocyte markers, such DLL1 and Jagged2 Notch ligands, whereas those ligands were significantly decreased in TGF-β1-treated keratinocytes. In conclusion, our findings suggest that the ASC-CM is a potent stimulator of human keratinocyte proliferation in vitro, particularly supporting basal keratinocytes, which are crucial for a successful skin coverage after transplantation. In contrast, TGF-β1 treatment decreased keratinocyte proliferation and specifically increased the expression of differentiation markers in vitro.

Integrative miRNA-mRNA profiling of human epidermis: unique signature of SCN9A painful neuropathy

Personalized management of neuropathic pain is an unmet clinical need due to heterogeneity of the underlying aetiologies, incompletely understood pathophysiological mechanisms and limited efficacy of existing treatments. Recent studies on microRNA in pain preclinical models have begun to yield insights into pain-related mechanisms, identifying nociception-related species differences and pinpointing potential drug candidates. With the aim of bridging the translational gap towards the clinic, we generated a human pain-related integrative miRNA and mRNA molecular profile of the epidermis, the tissue hosting small nerve fibres, in a deeply phenotyped cohort of patients with sodium channel-related painful neuropathy not responding to currently available therapies. We identified four miRNAs strongly discriminating patients from healthy individuals, confirming their effect on differentially expressed gene targets driving peripheral sensory transduction, transmission, modulation and post-transcriptional modifications, with strong effects on gene targets including NEDD4. We identified a complex epidermal miRNA-mRNA network based on tissue-specific experimental data suggesting a cross-talk between epidermal cells and axons in neuropathy pain. Using immunofluorescence assay and confocal microscopy, we observed that Nav1.7 signal intensity in keratinocytes strongly inversely correlated with NEDD4 expression that was downregulated by miR-30 family, suggesting post-transcriptional fine tuning of pain-related protein expression. Our targeted molecular profiling advances the understanding of specific neuropathic pain fine signatures and may accelerate process towards personalized medicine in patients with neuropathic pain.